Process for making fluorophthalimides

Abstract

Tri- or tetrafluorophthalimides are produced in a halogen-exchange reaction utilizing a metal fluoride salt and a dihydrocarbyl sulfoxide as the solvent. No phase-transfer catalyst is employed. The process has been found capable of producing the fully fluorinated phthalimide in yields of over 90% GC in reactions performed at 135-155 ° C. in reaction periods of as little as one hour even though no phase-transfer catalyst is employed.

That which is claimed is:  
     
       1. A process which comprises: 
       a) forming a phase-transfer catalyst-free reaction mixture comprised of (1) a tri- or tetrahalophthalimide in which at least one aromatic carbon atom in the molecule is substituted by a non-fluorine halogen atom, (2) a metal fluoride salt, (3) an inert hydrocarbyl sulfoxide solvent; and  
       b) maintaining said mixture at one or more temperatures in the range of about 135° C. to about 185° C. such that a compound is produced in which each non-fluorine halogen of the halophthalimide of a) which is attached to an aromatic carbon atom is replaced by a fluorine atom.  
     
     
       2. A process as in claim  1  wherein (3) is dimethyl sulfoxide. 
     
     
       3. A process as in claim  1  wherein the temperature in b) is in the range of about 135° C. to about 155° C. 
     
     
       4. A process as in claim  1  wherein (2) is potassium fluoride or sodium fluoride. 
     
     
       5. A process as in claim  1  wherein (2) is spray-dried finely-divided potassium fluoride or spray-dried finely-divided sodium fluoride. 
     
     
       6. A process as in claim  1  wherein the fluorophthalimide in b) is produced in a yield of at least about 80% GC, based on the initial molar quantity of said tri- or tetrahalophthalimide, in a reaction period of up to about two hours. 
     
     
       7. A process as in claim  1  wherein (2) is potassium fluoride or sodium fluoride, wherein (3) is dimethyl sulfoxide, and wherein the temperature in b) is in the range of about 135° C. to about 155° C. 
     
     
       8. A process as in claim  7  wherein fluorophthalimide in b) is produced in a yield of at least about 90% GC, based on the initial molar quantity of said tri- or tetrahalophthalimide, in a reaction period of up to about two hours. 
     
     
       9. A process as in claim  1  wherein said tri- or tetrahalophthalimide is characterized in that each of at least three aromatic carbon atoms in the molecule is substituted by a non-fluorine halogen atom. 
     
     
       10. A process as in claim  1  wherein (1) is a tetrachlorophthalimide. 
     
     
       11. A process as in claim  10  wherein (3) is dimethyl sulfoxide. 
     
     
       12. A process as in claim  10  wherein the temperature in b) is in the range of about 135° C. to about 155° C. 
     
     
       13. A process as in claim  10  wherein (2) is potassium fluoride or sodium fluoride. 
     
     
       14. A process as in claim  10  wherein (2) is spray-dried finely-divided potassium fluoride or spray-dried finely-divided sodium fluoride. 
     
     
       15. A process as in claim  10  wherein the fluorophthalimide in b) is produced in a yield of at least about 80% GC, based on the initial molar quantity of the tetrachlorophthalimide, in a reaction period of up to about two hours. 
     
     
       16. A process as in claim  10  wherein (2) is potassium fluoride or sodium fluoride, wherein (3) is dimethyl sulfoxide, and wherein the temperature in b) is in the range of about 135° C. to about 155° C. 
     
     
       17. A process as in claim  16  wherein tetrafluorophthalimide in b) is produced in a yield of at least about 90% GC, based on the initial molar quantity of said tetrachlorophthalimide, in a reaction period of up to about two hours. 
     
     
       18. A process as in claim  10  wherein said tetrachlorophthalimide is 3,4,5,6-tetrachloro-N-methylphthalimide, wherein (2) is potassium fluoride or sodium fluoride, wherein (3) is dimethyl sulfoxide, and wherein the temperature in b) is in the range of about 135° C. to about 155° C. 
     
     
       19. A process as in claim  18  wherein 3,4,5,6-tetrafluoro-N-methylphthalimide in b) is produced in a yield of at least about 90% GC, based on the initial molar quantity of 3,4,5,6-tetrachloro-N-methylphthalimide, in a reaction period of no more than about one hour. 
     
     
       20. A process as in claim  19  wherein (3) is spray-dried finely-divided potassium fluoride. 
     
     
       21. A process which comprises heating a reaction mixture formed from ingredients comprising (1) a tri- or tetrahalophthalimide in which at least one aromatic carbon atom is substituted by a non-fluorine halogen atom, (2) a metal fluoride salt, and (3) a hydrocarbyl sulfoxide solvent, said mixture being devoid of a phase-transfer catalyst, at a temperature in the range of about 135° C. to about 185° C. to produce a fluorophthalimide in which each non-fluorine halogen atom of the halophthalimide which is attached to an aromatic carbon is replaced by a fluorine. 
     
     
       22. A process as in claim  21  wherein said temperature is in the range of about 135° C. to about 155° C., wherein said sulfoxide is dimethyl sulfoxide, and wherein said metal fluoride salt is finely-divided potassium fluoride. 
     
     
       23. A process as in claim  22  wherein (1) is a 3,4,5,6-tetrachlorophthalimide. 
     
     
       24. A process as in claim  23  wherein the 3,4,5,6-tetrafluorophthalimide is produced in a yield of at least about 80% GC, based on the initial molar quantity of the 3,4,5,6-tetrachlorophthalimide, in a reaction period of up to about two hours. 
     
     
       25. A process as in claim  22  wherein (1) is a 3,4,5,6-tetrachloro-N-methylphthalimide. 
     
     
       26. A process as in claim  25  wherein the 3,4,5,6-tetrafluoro-N-methylphthalimide is produced in a yield of at least about 90% GC, based on the initial molar quantity of the 3,4,5,6-tetrachlorophthalimide, in a reaction period of up to about two hours. 
     
     
       27. A process as in claim  26  wherein said reaction period is no more than one hour.